Reference is made to U.S. Pat. No. 5,220,919 titled “BLOOD ALCOHOL MONITOR” and European Patent No. EPO 623001B1 titled “BLOOD ALCOHOL MONITOR”, both owned by the assignee of this invention and both are hereby incorporated herein by reference.
Individuals on probation, parole, or in alcohol treatment programs may be prohibited from consuming alcohol, and many federal, state, and local law enforcement agencies require testing to ensure participants in court ordered programs remain alcohol free. In general, present-generation remote alcohol monitoring devices used in probation, parole, and treatment settings are fixed-location breath-testing devices that utilize voice or video identification of the participant. If a subject tests positive for alcohol, the monitoring device then sends a message alerting the monitoring center of a violation by the subject, and the monitoring center then sends an alert message to the subject's supervising agency or dedicated administrator.
As alcohol is ingested orally, it is absorbed into the body's blood and distributed throughout the body via the circulatory system. Alcohol is eliminated from the body by two mechanisms: metabolism and excretion. Metabolism accounts for the removal of greater than 90% of the alcohol consumed, removing it from the body via oxidation of the ethyl alcohol molecule to carbon dioxide and water primarily in the liver. The remaining alcohol is excreted unchanged wherever water is removed from the body—breath, urine, perspiration, and saliva. Although excretion accounts for less than 10% of the eliminated alcohol, it is significant because unaltered alcohol excretion permits an accurate measurement of alcohol concentration in the body by way of both breath analysis and insensible skin perspiration. Insensible skin perspiration is the vapor that escapes through the skin through sweating. The average person will emit approximately one liter of insensible skin perspiration each day. This perspiration can be used to obtain a transdermal measurement of blood alcohol concentration, referred to as Transdermal Alcohol Concentration (“TAC”).
Transdermal monitoring of blood alcohol levels is accomplished by taking percentage measurements of alcohol contained in the air vapor that is expelled through human skin. A monitoring device is attached to the skin to capture the air and measure the alcohol. There are numerous advantages to transdermal monitoring, as opposed to breath alcohol testing, including, but not limited to, the ability to take readings at any time without the knowledge of the subject, consistent and continuous testing (unlike breath alcohol testing where a subject breathing incorrectly into the testing device can cause inaccurate results), and the ability to convert such readings into electrical signals that can be transmitted to a central monitoring station.
However, there is a continuing need for a remote alcohol monitoring system which can be conveniently placed on the subject that can carry out TAC measurements at selected time intervals as well as at random times. There is also a need for a remote alcohol monitoring system that will compensate for the effects of temperature changes on TAC readings, is tamper-proof, and virtually impossible for the subject to remove without triggering an alarm. Still further, there is also a need to be able to download the TAC measurements to a monitoring station without requiring any actions on the part of the subject being monitored, eliminating the need for the subject to personally report to a central monitoring station or probation officer, or connect the monitoring device to a telephone line to download and transmit data to a monitoring station. The present invention meets these and other needs in the art.